Intense panic and feeling of doom.

Over the past 2 years or so, initially started as a transient feeling of fear and panic which came and went for few months, but now, the anxiety of something bad happening in few minutes, like fear of dying etc strikes me if I am alone in a crowded place or a closed claustrophobic place etc. The symptoms are lightheadness, intense anxiety, restlessness with feet and hand tremors. Last year I did some tests which showed nothing else than vit d deficiency. Much recently, I feel intense panic when I about to ejaculate, mostly when I get over excited sexually. I have sleep problems too, although they come and go, and generally I feel better when in a safe space with family. Is it psychological? Or sex related? I don't smoke, drink or overweight, so any general family doctors tell me it's psychosomatic. Please share your opinions, thanks.